Taylor reactor for substance tranformation

ABSTRACT

In the Taylor reactor, in accordance with a first alternative of the invention, the reactor housing and/or the rotor are/is equipped such that the cross section of the reaction volume initially rises from the inlet to the outlet but the rise in cross section decreases in the direction of the outlet at least over part of the length of the rotor. In accordance with a second alternative of the invention, which may also find application in addition to the first, the end face of the rotor is designed in such a way that the reaction volume opens out into the outlet in such a way that it is at least substantially free from deadspaces ( FIG. 4 ).

The present invention relates to a Taylor reactor for physical and/orchemical conversions in the course of which there is an increase in theviscosity of the reaction medium. Moreover, the present inventionrelates to a novel process for conversion by means of the Taylorreactor, and to the use of the substances prepared by the novel process.

Taylor reactors, which serve to convert substances under the conditionsof Taylor vortex flow, have long been known. In their originalembodiment they are composed of two coaxial concentric cylinders ofwhich the outer is fixed while the inner rotates. The reaction spaceused is the volume formed between the inner periphery of the outercylinder and the outer periphery of the inner cylinder. Increasingangular velocity of the inner cylinder is accompanied by a series ofdifferent flow patterns which are characterized by a dimensionlessparameter, known as the Taylor number Ta. As well as on the angularvelocity of the inner cylinder, which forms the rotor, the Taylor numberis also dependent on the kinematic viscosity of the fluid in thereaction volume and on the geometric parameters, the external radius ofthe inner cylinder, r_(i), and the internal radius of the outercylinder, r_(o), in accordance with the following formula:Ta=ω _(i) r _(i) d ν ⁻¹(d/r _(i))^(1/2)  (I)where d=r_(o)−r_(i).

At low angular velocity, the laminar Couette flow, a simple shear flow,is developed. If the rotary speed of the inner cylinder is increasedfurther, then, above a critical level, alternately contrarotatingvortices (rotating in opposition) occur, with axes along the peripheraldirection. The vortices, called Taylor vortices, are rotationallysymmetric, possess the geometric form of a torus (Taylor vortex ring),and have a diameter which is approximately the same size as the gapwidth. Two adjacent vortices form a vortex pair or vortex cell.

The basis of this behavior is the fact that, in the course of rotationof the inner cylinder with the outer cylinder at rest, the fluidparticles near the inner cylinder are subject to a greater centrifugalforce than those at a greater distance from the inner cylinder. Thisdifference in the acting centrifugal forces displaces the fluidparticles from the inner to the outer cylinder. The viscosity force actscounter to the centrifugal force, since for the fluid particles to moveit is necessary for the friction to be overcome. Any increase in therotary speed is accompanied by an increase in the centrifugal force. TheTaylor vortices are formed when the centrifugal force exceeds thestabilizing viscosity force.

If the Taylor reactor is provided with an inlet and an outlet and isoperated continuously, the result is a Taylor vortex flow with a lowaxial flow. Each vortex pair passes through the gap, with only a lowlevel of mass transfer between adjacent vortex pairs. Mixing within suchvortex pairs is very high, whereas axial mixing beyond the pairboundaries is very low. A vortex pair may therefore be regarded as astirred tank in which there is thorough mixing. Consequently, the flowsystem behaves as an ideal flow tube in that the vortex pairs passthrough the gap with a constant residence time, like idealstirred-tanks.

If, however, as conversion progresses there is a sharp change in theviscosity ν of the fluid in the axial flow direction, as is the casewith bulk polymerization, then the Taylor vortices disappear or are noteven formed. In that case, Couette flow, a concentric, laminar flow, isobserved in the annular gap and there is an unwanted change in themixing and flow conditions within the Taylor reactor. In this operatingstate the reactor exhibits flow characteristics which are comparablewith those of the laminarly flow-traversed tube, which is a considerabledisadvantage. For example, during bulk polymerization there is anundesirably broad molar mass distribution and chemical nonuniformity ofthe polymers. Moreover, the adverse reaction regime may result inconsiderable quantities of residual monomers, which must then bedischarged from the Taylor reactor. However, there may also be instancesof coagulation and polymer deposition, which in some cases may even leadto blockage of the reactor or of the product outlet. All in all it is nolonger possible to obtain the desired products, such as polymers havingcomparatively narrow molar mass distribution, for instance, the productswhich result instead being only those whose profile of properties failsto match the requirements.

DE 198 28 742 A1 discloses a Taylor reactor which in order to solvethese problems has been given

-   -   a) an external reactor wall located within which there is a        concentrically disposed rotor, a reactor floor, and a reactor        lid, which together define the annular reaction volume,    -   b) at least one means for metered addition of reactants, and    -   c) a means for the discharge of product,        where there is a widening, in particular a conical widening, in        the annular reaction volume in the flow direction. As a result,        the known Taylor reactor is able substantially to solve the        problem of maintaining the Taylor flow when there is a sharp        increase in the kinematic viscosity ν in the reaction medium.

In this known Taylor reactor, the annular reaction volume is defined bythe concentrically disposed rotor, the reactor floor, and the reactorlid. This means that the product outlet has to be disposed on the sideof the Taylor reactor or in the reactor lid, and cannot be designedwithout edges. With this configuration, however, it is difficult torealize undisrupted product discharge.

Owing to the deleterious interaction of flow and geometricconfiguration, on the one hand, the known Taylor reactor is still unableto solve all of the safety and engineering problems which occur in thecourse of bulk polymerization and, on the other hand, it is still notpossible to increase the monomer conversion to an extent such thatsubstantial freedom from monomers and a narrow molecular weightdistribution and molecular weight polydispersity of the polymers areachieved.

Although the problem of inadequate mixing of the reactants can be solvedto a certain extent by inserting a mixing unit upstream of the entry ofthe reactants, as is described in German patent application DE 199 60389 A1, the problems outlined above which affect bulk polymerizationstill occur.

American patent U.S. Pat. No. 4,174,097 discloses a Taylor reactor inwhich the rotor is mounted rotatably in the inlet region for thereactants. At its other end, the rotor is not mounted but instead endsessentially before the outlet region, which at its widest point has thesame diameter as the external reactor wall. The outlet region narrows inthe manner of a funnel to form an outlet pipe. The known Taylor reactorserves for the mixing of liquids differing in viscosity and electricalconductivity. It may also serve for reaction of polyisocyanates withpolyols. To what extent it may be used for the bulk polymerization ofolefinically unsaturated monomers, the American patent does not reveal.

In the case of the known Taylor reactor, the driveshaft is guidedthrough the reactor floor and is connected to the rotor in the inletregion of the reactants. However, there is no widening in the annularreaction volume in the flow direction. Although the American patentspecifies, in column 10 lines 29 to 33, that the concentric parts mayalso have configurations other than the cylindrical—for example,substantially spherical or conical configurations—there is no teachingas to which configurations are especially advantageous for bulkpolymerization.

Despite the fact that, with the Taylor reactors having a reaction volumewidening in the flow direction, it was possible to increase themonomeric conversions and to reduce the formation of gel particles, thepolydispersities found for the preparation of polyacrylate resinswere >3. Conversions >99% were realizable only when a certain amount ofacrylate monomer was present.

It is an object of the present invention, accordingly, to reduce thepolydispersities while at the same time raising the conversion rate.

This object is achieved by the Taylor reactors reproduced in theindependent claims 1, 10 and 13. References below to a “Taylor reactor”are intended to express the fact that, viewed in the direction of theaxis of rotation of the rotor, in other words in the flow direction ofthe reaction medium, Taylor vortices are formed at least over onesubregion of the reaction volume while the reactor is in operation.

Surprisingly it has been found that, with a Taylor reactor in which thereactor housing and/or the rotor are configured such that the crosssection of the reaction volume rises, at least to start with, from theinlet to the outlet but in the direction of the outlet—that is, in theflow direction of the reaction medium—there is a decrease in the rise,at least over part of the length of the rotor, it is possible to achievea marked reduction in the polydispersities. One possible explanation forthis effect is the reduction or even prevention of short-circuit flowsat the edges delimiting the reaction volume, which may form if theTaylor vortices do not extend up to the edges. By “short-circuit flow”,therefore, is meant a flow within the reactor in the flow direction ofthe reaction media, which partially circumvents the mixing operation andso reduces the residence time in the reactor, leading to lower degreesof polymerization.

Experiments have shown that the Taylor reactor of the invention is,surprisingly, suitable for all conversions where there was a sharpchange in the kinematic viscosity ν of the reaction medium in the flowdirection.

Particularly surprising is that the Taylor reactor of the invention andthe process of the invention allow the free-radical, anionic, andcationic (co)polymerization, graft copolymerization, and blockcopolymerization (referred to collectively as “polymerization”) ofolefinically unsaturated monomers in bulk with conversion rates >70 mol%. Even more surprising is that conversion rates >98 mol % can beobtained without problems in the Taylor reactor of the invention withoutthe formation of disruptive gas bubbles and/or the deposition of(co)polymers, graft copolymers, and block copolymers (referred tocollectively as “polymers”).

A further surprise is that the Taylor reactor of the invention and theprocess of the invention allow a particularly safe bulk polymerizationreaction regime, allowing the polymers to be produced very safely,reliably, and reproducibly. Owing to the very low levels of monomer inthe polymers, they can be put to a very wide variety of end uses withoutadditional purification and without the occurrence of safety,engineering, toxicological or environmental problems or odor nuisance.

The Taylor reactor of the invention preferably comprises an annularreaction volume which preferably has a circular periphery. The annularreaction volume is defined or formed by an outer reactor wall locatedwithin which there is a concentrically disposed rotor which is disposedso as to be rotatable around the axis of rotation.

Over the entire length of the reaction volume, as viewed in crosssection, the external reactor wall and the rotor have a circularperiphery. The term “circular” means strictly circular, oval, ellipticalor polygonal with rounded angles. For reasons of greater ease ofmanufacture, simplicity of construction and significantly greater easeof maintaining constant conditions over the entire length of the annularreaction volume, a strictly circular periphery is of advantage.

The internal wall of the external reactor wall and/or the surface of therotor may be smooth or rough, i.e., the surfaces in question may have alow or high roughness. Additionally or alternatively, the internal wallof the external reactor wall and/or the surface of the rotor may have arelieflike radial and/or axial, preferably radial, surface profile, asdescribed, for example, in American patent U.S. Pat. No. 4,174,90 A orBritish patent GB 1 358 157. If there is a radial surface profile, it isadvantageously of approximately or exactly the same dimensions as theTaylor vortex rings.

It is of advantage, however, for the internal wall of the externalreactor wall and the surface of the rotor to be smooth and unprofiled,in order to prevent dead corners into which gas bubbles or reactants,process media, and products might settle.

Viewed in the lengthwise direction, the Taylor reactor of the inventionis mounted vertically, horizontally or in a position between these twodirections. Vertical mounting is advantageous. If the Taylor reactor ofthe invention is not mounted horizontally, it may be traversed by thereaction medium flowing against gravity, from bottom to top, or withgravity, from top to bottom. In accordance with the invention it isadvantageous if the reaction medium is moved counter to gravity.

By influencing the rate at which the reaction medium passes through thereactor, by varying the feed rate at the inlet, it is possible toinfluence the course of viscosity in the reaction medium. The reactorcan therefore be used for various reaction mixtures.

In accordance with the invention, the rise in the cross section of thereaction volume in the flow direction decreases continuously ordiscontinuously, especially continuously, in accordance with appropriatemathematical functions. Examples of appropriate mathematical functionsare straight lines, at least two straight lines which intersect oneanother at an obtuse angle, parabolas, hyperbolas, e functions orcombinations of these functions with continuous or discontinuoustransitions, especially continuous transitions, between them. Themathematical functions are preferably straight lines; in other words,the preferably annular cross section of the reaction volume in the flowdirection widens constantly in a first section at a greater rate than ina second section, in which the cross section widens to a lesser extent,and is preferably constant. The extent of the widening is guided by theanticipated increase in the viscosity of the reaction medium in the flowdirection and can be estimated by the skilled worker on the basis of theTaylor formula I and/or determined by the skilled worker on the basis ofsimple preliminary experiments.

In the context of the widening of the cross section of the annularreaction volume, the external reactor wall may be cylindrical and therotor conical in shape, with the rotor having the greatest diameter onthe inlet side. Alternatively, the external reactor wall may be conicalin shape and the rotor cylindrical, i.e., with its cross sectionconstant over the entire length of the rotor. In accordance with theinvention it is advantageous if the external reactor wall is conical ina first, inlet-side region and cylindrical in a second region, and therotor is cylindrical.

If the outlet is disposed axially, i.e., if it opens out into thereaction volume in the direction of the rotational axis of the rotor,the supply of the reactants and/or of the process media brings aboutflow in the reaction volume in the direction of the outlet and throughthe outlet.

In the case of a further constructional design of a Taylor reactor, theflow about the rotational axis is also utilized as a driving force forthe removal of the reaction products, in that the outlet opens out intothe reaction volume radially at a distance from the rotational axis.

The angle of opening out between the rotational axis and the outlet linedefined by the outlet is arbitrary. It is preferred, however, if outletline and rotational axis form an angle of between 0° and 90°, i.e., ifthe outlet opens out into the reaction volume transversely with respectto the rotational axis.

Particularly when the outlet extends approximately perpendicular to therotational axis in the region of opening out, the component of the flowaround the rotational axis, as a fraction of the driving force for theremoval of the reaction products, reaches its maximum. In this case itis advantageous to design the end adjacent to the outlet in the mannerof a pump rotor, in order to generate as great as possible a flow aboutthe rotational axis in this region.

This can be done without adverse consequences for the reaction procedurewithin the reactor, since owing to the high viscosity and the fact thata conversion rate of approximately 99% has already been achieved thereis no longer any need for Taylor vortices or reaction procedures.

In the narrowest region of the annular reaction volume, located abovethe reactor floor, there is at least one inlet for the reactants,especially for the olefinically unsaturated monomers, and for suitableprocess media, such as catalysts and initiators. The inlet may bedisposed laterally or may pass through the reactor floor. Preferablythere are at least two inlets, which are disposed laterally and/or passthrough the reactor floor. Where appropriate, it is possible in the flowdirection to provide further inlets, through which further reactants,catalysts or initiators can be metered in, so that the conversions,particularly the polymerization, may be conducted in a plurality ofstages.

The reactants can be supplied to the inlet by means of conventionaltechniques and means, such as metering pumps. The means may be equippedwith conventional mechanical, hydraulic, optical, and electronicmeasurement and control devices. Additionally, it is possible to insert,upstream of the inlet, one of the mixing means described, for example,in German patent application DE 199 60 389 A1, column 4 line 55 tocolumn 5 line 34.

In the case of the inventive Taylor reactor as claimed in claim 10,there is an outlet region which tapers in the flow direction toward aproduct outlet.

The end face of the rotor, i.e., the end facing the outlet, is designedso that the reaction volume opens out into the product outlet with atleast substantially no dead spaces.

The outlet region and the product outlet are defined by the externalreactor wall.

The tapering of the outlet region may be described by the mathematicalfunctions set out above, preference being given to straight lines.Accordingly, the tapering of the outlet region is preferably conical. Inthat case the end face of the rotor is preferably of conical design, inorder—as is preferred—to ensure that the cross section of the outletregion is substantially constant in the direction of the axis. Theresult of this is to prevent dead spaces, while at the same time notgiving rise to any adverse pressure buildup.

The reactor wall in the inlet region, in the region of the annularreaction volume, and in the outlet region, and also the inlet or inletsand the product outlet, may be equipped with a heating or coolingjacket, allowing heating or cooling to be carried out in cocurrent or incountercurrent. Moreover, the Taylor reactor of the invention maycontain conventional mechanical, hydraulic, optical, and electronicmeasurement and control means, such as temperature sensors, pressuremeters, flow meters, optical or electronic sensors, and devices formeasuring concentrations, viscosities, and other physicochemicalvariables, these devices passing on their measured data to a dataprocessing unit, which controls the entire process sequence.

The Taylor reactor of the invention is preferably of pressuretightdesign, so that the reaction medium may stand preferably under apressure of from 1 to 100 bar. The Taylor reactor of the invention maybe made of any of a wide variety of materials, provided they are notattacked by the reactants or reaction products and they withstand arelatively high pressure. It is preferred to use metals, preferablysteel, particularly stainless steel.

The Taylor reactor of the invention can be put to a very wide variety ofend uses. It is preferably used for conversions in the course of whichthere is a rise in the kinematic viscosity ν of the reaction medium inthe flow direction.

Examples of conversions which can be carried out in the Taylor reactorof the invention with particular advantages are the synthesis ordegradation of oligomeric and high molecular mass substances, such asthe polymerization of monomers in bulk, solution, emulsion orsuspension, or by precipitation polymerization.

Further examples of such conversions are

-   -   polymer-analogous reactions, such as the esterification,        amidation or urethanization of polymers containing side groups        suitable for such reactions,    -   the preparation of olefinically unsaturated materials curable        using electron beams or ultraviolet light,    -   the preparation of polyurethane resins and modified polyurethane        resins such as acrylated polyurethanes,    -   the preparation of (poly)ureas or modified (poly)ureas,    -   the molecular weight buildup of compounds terminated by        isocyanate groups,    -   or reactions which lead to the formation of mesophases, as        described, for example, by Antonietti and Göltner in the article        “Überstruktur funktionneller Kolloide: eine Chemie im        Nanometerbereich” [Superstructure of functional colloids: a        chemistry in the nanometer range] in Angewandte Chemie        109 (1997) 944 to 964, or by Ober and Wengner in the article        “Polyelectrolyte-Surfactant Complexes in the Solid State: Facile        Building Blocks for Self-Organizing Materials” in Advanced        Materials 9 (1997) 1, 17 to 31.

With very particular advantage, the process of the invention is employedfor the polymerization of olefinically unsaturated monomers in bulk,since in that case the particular advantages of the Taylor reactor ofthe invention are manifested with particular clarity.

Accordingly, the Taylor reactor of the invention is used with particularpreference for preparing polymers and copolymers of chemically uniformcomposition. In the case of copolymerization, the more rapidlypolymerizing comonomer or comonomers can be metered in by way of inletsdisposed in succession in the axial direction, so that the comonomerratio can be kept constant over the entire length of the reactor.

The Taylor reactor is also used with particular advantage for graftcopolymerization.

In this case, the backbone polymer, as it is known, can be preparedseparately and introduced into the Taylor reactor of the invention byway of a separate inlet or in a mixture with at least one monomer.

Alternatively, the backbone polymer can be prepared in a firstsubsection of the Taylor reactor of the invention, after which at leastone monomer which forms the graft branches is metered in by way of atleast one further inlet, offset in the axial direction. Subsequently,the monomer or comonomers can be grafted onto the backbone polymer in atleast one further subsection of the Taylor reactor of the invention.Where two or more comonomers are used, they may be metered inindividually by way of one inlet in each case or as a mixture, throughone inlet or two or more inlets. Where at least two comonomers aremetered in individually and in succession through at least two inlets,it is even possible to prepare graft branches which viewed per se areblock copolymers, in a particularly simple and elegant manner.

Naturally, this concept as described above may also be used to prepareblock copolymers per se.

Analogously, the Taylor reactor of the invention can be used toeffectuate the preparation of core/shell lattices in a particularlysimple and elegant manner. Initially, in the first subsection of theTaylor reactor of the invention, the core is prepared by polymerizing atleast one monomer. By way of at least one further inlet, at least onefurther comonomer is metered in and the shell is polymerized onto thecore in at least one further subsection. In this way it is possible toapply a plurality of shells to the core.

The preparation of polymer dispersions may also be effected by means ofthe Taylor reactor of the invention. For example, at least one monomerin a homogeneous phase, particularly in solution, is (co)polymerized ina first subsection of the Taylor reactor of the invention, after which aprecipitant is metered in by way of at least one further means,resulting in the polymer dispersion.

For all applications, the Taylor reactor of the invention has theparticular advantage of a large specific cooling area, which allows aparticularly safe reaction regime.

With very particular preference, the Taylor reactor of the invention isused for the continuous preparation of (co)polymers, block copolymers,and graft copolymers by free-radical, anionic or cationic, especiallyfree-radical, (co)polymerization, block copolymerization or graftcopolymerization (polymerization) of at least one olefinicallyunsaturated monomer in bulk by the process of the invention.

Examples of monomers suitable for the process of the invention areacyclic and cyclic, unfunctionalized and functionalized monoolefins anddiolefins, vinylaromatic compounds, vinyl ethers, vinyl esters, vinylamides, vinyl halides, allyl ethers, and allyl esters, acrylic acid andmethacrylic acid and their esters, amides, and nitrites, and maleicacid, fumaric acid, and itaconic acid and their esters, amides, imides,and anhydrides.

Examples of suitable monoolefins are ethylene, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, cyclobutene, cyclopentene,dicyclopentene, and cyclohexene.

Examples of suitable diolefins are butadiene, isoprene, cyclopentadiene,and cyclohexadiene.

Examples of suitable vinylaromatic compounds are styrene,alpha-methylstyrene, 2-, 3-, and 4-chloro-, -methyl-, -ethyl-, -propyl-,and -butyl- and -tert-butylstyrene and -alpha-methylstyrene.

One example of a suitable vinyl compound or of a functionalized olefinis vinylcyclohexanediol.

Examples of suitable vinyl ethers are methyl, ethyl, propyl, butyl, andpentyl vinyl ether, allyl monopropoxylate, and trimethylolpropanemonoallyl, diallyl, and triallyl ether.

Examples of suitable vinyl esters are vinyl acetate and vinyl propionateand also the vinyl esters of Versatic acid and other quaternary acids.

Examples of suitable vinyl amides are N-methyl-, N,N-dimethyl-,N-ethyl-, N-propyl-, N-butyl-, N-amyl-, N-cyclopentyl-, andN-cyclohexylvinylamide and also N-vinylpyrrolidone andN-epsilon-caprolactam.

Examples of suitable vinyl halides are vinyl fluoride and vinylchloride.

Examples of suitable vinylidene halides are vinylidene fluoride andvinylidene chloride.

Examples of suitable allyl ethers are methyl, ethyl, propyl, butyl,pentyl, phenyl, and glycidyl monoallyl ether.

Examples of suitable allyl esters are allyl acetate and allylpropionate.

Examples of suitable esters of acrylic acid and methacrylic acid aremethyl, ethyl, propyl, n-butyl, isobutyl, n-pentyl, n-hexyl,2-ethylhexyl, isodecyl, decyl, cyclohexyl, t-butylcyclohexyl, norbornyl,isobornyl, 2- and 3-hydroxypropyl, 4-hydroxybutyl, trimethylolpropanemono- pentaerythritol mono-, and glycidyl (meth)acrylate. Also suitableare the di-, tri-, and tetra(meth)acrylates of ethylene glycol, di-,tri-, and tetraethylene glycol, propylene glycol, dipropylene glycol,butylene glycol, dibutylene glycol, glycerol, trimethylolpropane, andpentaerythritol. However, they are used not alone but always in minoramounts together with the monofunctional monomers.

Examples of suitable amides of acrylic acid and methacrylic acid are(meth)acrylamide and also N-methyl-, N,N-dimethyl-, N-ethyl-, N-propyl-,N-butyl-, N-amyl-, N-cyclopentyl-, and N-cyclohexyl(meth)acrylamide.

Examples of suitable nitriles are acrylonitrile and methacrylonitrile.

Examples of suitable esters, amides, imides, and anhydrides of maleic,fumaric, and itaconic acids are dimethyl, diethyl, dipropyl, and dibutylmaleate, fumarate, and itaconate, maleamide, fumaramide, anditaconamide, N,N′-dimethyl-, N,N,N′,N′-tetramethyl-, N,N′-diethyl-,N,N′-dipropyl-, N,N′-dibutyl-, N,N′-diamyl, N,N′-dicyclopentyl andN,N′-dicyclohexyl-maleamide, fumaramide, and itaconamide, maleimide,fumarimide, and itaconimide, and N-methyl-, N-ethyl-, N-propyl-,N-butyl-, N-amyl-, N-cyclopentyl-, and N-cyclohexyl-maleimide,-fumarimide, and -itaconimide, and also maleic anhydride, fumaricanhydride, and itaconic anhydride.

The monomers described above may be polymerized free-radically,cationically or anionically. Advantageously they are polymerizedfree-radically. For this purpose it is possible to use the conventionalinorganic free-radical initiators such as hydrogen peroxide or potassiumperoxodisulfate or the conventional organic free-radical initiators suchas dialkyl peroxides, e.g., di-tert-butyl peroxide, di-tert-amylperoxide, and dicumyl peroxide; hydroperoxides, e.g., cumenehydroperoxide and tert-butyl hydroperoxide; peresters, e.g., tert-butylperbenzoate, tert-butyl perpivalate, tert-butylper-3,5,5-trimethylhexanoate, and tert-butyl per-2-ethylhexanoate;disazo compounds such as azobisisobutyronitrile; or C-C initiators suchas 2,3-dimethyl-2,3-diphenyl-butane or -hexane. Also suitable, however,is styrene, which initiates polymerization thermally even withoutfree-radical initiators.

In the process of the invention, at least one of the above-describedmonomers is metered via a lateral inlet into the inlet region of theTaylor reactor of the invention. It is preferred to meter at least oneof the above-described free-radical initiators, preferably together withat least one monomer, via a further lateral inlet.

The monomer or monomers is or are polymerized within the reaction volumeat least partly under the conditions of Taylor flow. The resultantliquid polymer is conveyed from the annular reaction volume into theoutlet region and from there into the product outlet, and is dischargedby way of the pressure maintenance valve.

Preferably, in the process of the invention, the conditions for Taylorflow are met in part of the annular reaction volume or in the entireannular reaction volume, especially in the entire annular reactionvolume.

The temperature of the reaction medium in the process of the inventionmay vary widely and is guided in particular by the monomer having thelowest decomposition temperature, by the temperature at whichdepolymerization sets in, and by the reactivity of the monomer ormonomers and of the initiators. Preferably the polymerization isconducted at temperatures from 100 to 200° C., more preferably from 130to 180° C., and in particular from 150 to 180° C.

The polymerization may be carried out under pressure. The pressure ispreferably from 1 to 100 bar, more preferably from 1 to 25 bar, and inparticular from 1 to 15 bar.

The traversal time may vary widely and depends in particular on thereactivity of the monomers and on the size, especially the length, ofthe Taylor reactor of the invention. The traversal time is preferablyfrom 15 minutes to 2 hours, in particular from 20 minutes to 1 hour.

It is a very particular advantage of the Taylor reactor of the inventionand of the process of the invention that the conversion of the monomersis >70 mol %.

Surprisingly it is possible without problems to achieve conversions >80,preferably >90, with particular preference >95, with very particularpreference >98, and in particular >98.5 mol %. As is customary in thecase of bulk polymerization, it is possible in the course of suchconversions for the kinematic viscosity ν to increase by a factor of atleast ten, in particular at least one hundred.

The molecular weight of the polymers prepared by means of the process ofthe invention may vary widely and is limited essentially only by themaximum kinematic viscosity ν at which the Taylor reactor of theinvention is able to maintain the conditions of Taylor flow. The numberaverage molecular weights of the polymers prepared in an inventiveprocedure are preferably from 800 to 50,000, more preferably from 1,000to 25,000, and in particular from 1,000 to 10,000 daltons. The molecularweight polydispersity is preferably <10, in particular <8.

The drawings show exemplary embodiments of the invention; specifically

FIG. 1 shows—diagrammatically—an exemplary embodiment of a Taylorreactor of the invention in accordance with the first alternative of theinvention, in longitudinal section;

FIG. 2 shows a further exemplary embodiment of a Taylor reactor of theinvention in accordance with the first alternative of the invention, ina representation corresponding to that of FIG. 1;

FIG. 3 shows an exemplary embodiment of a Taylor reactor of theinvention in accordance with the second alternative of the invention, ina view corresponding to that of FIG. 1;

FIG. 4 shows an exemplary embodiment of a Taylor reactor of theinvention, in which both alternatives of the invention are realized, ina view corresponding to that of FIGS. 1 and 2;

FIG. 5 shows an exemplary embodiment of a Taylor reactor of theinvention in accordance with the third alternative of the invention, ina view corresponding to that of FIG. 1; and

FIG. 6 shows a section along the line VI-VI in FIG. 5.

The Taylor reactor which as a whole is designated by 100 in FIG. 1comprises a reactor housing 103 whose lower region—lower, that is, inaccordance with the representation in FIG. 1, which corresponds to thenormal operating position of the Taylor reactor 100—is designed as aninsertion region 108. Opening out into said region 108 are two inlets108.1, which are opposite one another laterally and through which it ispossible to supply the reactants and/or process media to the reactionvolume 102, which is formed between the outer periphery 104.3 of acylindrical rotor 104 and the inner periphery 103.1 of the reactorhousing 103.

The section 103.2 of the reactor housing 103 that adjoins the inletregion 108 is configured so as to widen conically upward until itreaches the point 103.3, so that the cross section of the reactionvolume 102 rises in the section 103.2. Moving upward, the point 103.3 isfollowed by a cylindrical section 103.4 of the reactor housing 103,which extends to beyond the upper end face 104.2 of the rotor 104.Following the cylindrical section 103.4 is an outlet region 109 whichruns together in the shape of a funnel and which opens out into anoutlet 110, which is used to discharge the reaction products. Downstreamof the outlet 110 is a pressure maintenance valve 111 which can be usedto maintain the reaction media under a predeterminable pressure withinthe reaction volume.

The rotor 104 is mounted on the inlet-side end wall 105, shown at thebottom in FIG. 1 so as to be rotatable around an axis A. Introduction ofa torque which brings about rotation in the rotor 104 is effected by adriveshaft 107, which is passed through the end wall 105 and isconnected with a rotary drive—an electric motor, for example—which isnot shown in the drawing. The sealing of the reaction volume 102 in theregion where the driveshaft 107 passes through the end wall 105 iseffected by a gasket 106, which is arranged between the end wall 105 andthe end 104.1 of the rotor 104, which is shown at the bottom in thedrawing.

For the purpose of premixing the reactants and/or process media whichare supplied to the reaction volume, it is possible for one or moreinlets to be equipped with mixers 112.

As apparent from FIG. 1, the design of the reactor housing 103 and ofthe rotor 104 has the effect that the cross section of the reactionvolume, as viewed from inlet to outlet, initially rises in section 103.2of the reactor housing but from the point 103.3 the rise decreases—inthe exemplary embodiment depicted, to a value of 0—to the outlet in thecylindrical housing section 103.4.

The exemplary embodiment depicted in FIG. 2 agrees in large part withthat of FIG. 1 in terms of its technical configuration. In order to saverepetition, only the differences will be illustrated below. Componentscorresponding to the exemplary embodiment of FIG. 1 have been givenreference numerals increased by 100.

In the case of the exemplary embodiment depicted in FIG. 2, the reactorhousing 203 is designed with a conical widening up to the outlet region209. In order to bring about the inventive decrease in the rise of thecross section of the reaction volume of the outlet, the rotor 204, whichis designed cylindrically in its region which is at the bottom inaccordance with FIG. 2, has a point 204.3 starting from which itundergoes transition to the region 204.4, which widens conically to theoutlet region 209. The conicity corresponds to that of the reactorhousing 203, so that the cross section of the reaction volume from point204 to the top end of the rotor remains constant.

In the case of the Taylor reactor which is designated as a whole by 301and is depicted in FIG. 3, and which is an exemplary embodiment inaccordance with the second alternative of the invention, again only thedifferences from the Taylor reactor according to FIG. 1 will beaddressed. Reference is again made to the description relating to FIG.1, the corresponding components in FIG. 3 having been given referencesymbols increased by 200.

The reactor housing 303 of the Taylor reactor 301 is designed so as towiden conically from the inlet region 308 to the outlet region 309. Therotor 304 has a cylindrical design, which at the point 304.3 undergoestransition to a cone 313. The cone angle d is chosen so that the conesurface 314 runs parallel to the wall 303.4 of the reactor housing 303,said wall delimiting the outlet region 309. By this means, the reactionvolume opens out into the outlet 310 in a way which is at leastsubstantially deadspace-free. This effectively prevents parts of thereaction medium being deposited above the rotor 304, which would lead tounwanted, further polymerization by prolonging the residence time in thereactor.

FIG. 4 shows one particularly preferred exemplary embodiment of a Taylorreactor of the invention, in which both alternatives of the inventionhave been realized. The Taylor reactor, now designated 401, comprises areactor housing 403 which corresponds to that depicted in FIG. 1. Therotor 404, like that in FIG. 3, has been provided at its top end with acone 413.

In this particularly preferred embodiment, therefore, both short circuitflows in the reaction volume 402 and the formation of deadspaces in theoutlet region 409 are prevented.

1. A Taylor reactor (101, 201, 301, 401) comprising a reactor housing(103, 203, 303, 403), having a rotor (104, 204, 304, 404) which isdisposed in the volume enclosed by the reactor housing (103, 203, 303,403) and is rotatable about an axis, having a reaction volume (102, 202,302, 402) formed between the inner periphery of the reactor housing(103, 203, 303, 403) and the outer periphery (104.3, 204.3, 304.3,404.3) of the rotor (104, 204, 304, 404), having at least one inlet(108.1, 208.1, 308.1, 408.1) for the reactants and/or process media andhaving at least one outlet (110, 210, 310, 410) for the reactionproducts, disposed in the direction of the axis (A) at a distance fromthe inlet (108.1, 208.1, 308.1, 408.1), wherein the reactor housing(103, 203, 303, 403) and/or the rotor (104, 204, 304, 404) are equippedsuch that the cross section of the reaction volume (102, 202, 302, 402)initially rises from the inlet (108.1, 208.1, 308.1, 408.1) to theoutlet (110, 210, 310, 410) but the rise in cross section does notincrease at least over part of the length of the rotor (104, 204, 304,404).
 2. A Taylor reactor as claimed in claim 1, wherein the rotor (104,204, 304, 404) is disposed concentrically in the reactor housing (103,203, 303, 403).
 3. A Taylor reactor as claimed in claim 1, wherein thereaction volume (102, 202, 302, 402) is of annular design.
 4. A Taylorreactor as claimed in claim 3, wherein the reaction volume (102, 202,302, 402) has a circular periphery.
 5. A Taylor reactor as claimed inclaim 1, wherein the decrease in the rise of the cross section of thereaction volume (102, 202, 302, 402) is continuous.
 6. A Taylor reactoras claimed in claim 1, wherein the decrease in the rise of the crosssection of the reaction volume (102, 202, 302, 402) is discontinuous. 7.A Taylor reactor as claimed in claim 6, wherein at least one of thereactor housing (103, 203, 303, 403) or the rotor (104, 204, 304, 404)have, in the direction of the axis (A), at least two sections whoseinner periphery and/or outer periphery form(s) different angles withrespect to the axis (A).
 8. A Taylor reactor as claimed in claim 1,wherein the ratio of the radius of the reactor housing (r_(o)) to theradius of the rotor (r_(i)) at least for part of the length of thereaction volume (102, 202, 302, 402) is <1.4.
 9. A Taylor reactor asclaimed in claim 1, wherein the rotor (104, 204, 304, 404) iscylindrical.
 10. A Taylor reactor having a reactor housing (103, 203,303, 403), having a rotor (104, 204, 304, 404) which is disposed in thevolume enclosed by the reactor housing (103, 203, 303, 403) in such away as to be rotatable about an axis (A), having a reaction volume (102,202, 302, 402) formed between the inner periphery (103.1, 203.1, 303.1,403.1) of the reactor housing (103, 203, 303, 403) and the outerperiphery (104.3, 204.3, 304.3, 404.3) of the rotor (104, 204, 304,404), having at least one inlet (108.1, 208.1, 308.1, 408.1) for thereactants and/or process media, in particular as claimed in claim 1,wherein an outlet region (109, 209, 309, 409) which opens out into anoutlet (110, 210, 310, 410) is provided which in the reactor housing(103, 203, 303, 403) at one end face of the rotor (104, 204, 304, 404)adjoins the reaction volume (102, 202, 302, 402) and narrows to anoutlet (110, 210, 310, 410) and wherein the end face of the rotor (104,204, 304, 404) is designed such that the reaction volume (102, 202, 302,402) opens out at least essentially without deadspaces into the outlet(110, 210, 310, 410).
 11. A Taylor reactor as claimed in claim 10,wherein the end face of the rotor (104, 204, 304, 404) is designed suchthat in the direction of the axis (A) the cross section of the outletregion (109, 209, 309, 409) is at least substantially constant.
 12. ATaylor reactor as claimed in claim 10 or 11, wherein the reactor housing(103, 203, 303, 403) is configured such that the outlet region (109,209, 309, 409) is in the shape of a funnel and the end face of the rotor(104, 204, 304, 404) is of conical design.
 13. A Taylor reactor having areactor housing (503), having a rotor (504) which is disposed in thevolume enclosed by the reactor housing (503) in such a way as to berotatable about an axis (A), having a reaction volume (502) formedbetween the inner periphery (503.1) of the reactor housing (503) and theouter periphery (504.3) of the rotor (504), having at least one inlet(508.1) for the reactants and/or process media and having at least oneoutlet (510) for the reaction products, in particular as claimed inclaim 1, wherein the outlet (510) opens out into the reaction volume(502) at a radial distance from the axis (A).
 14. A Taylor reactor asclaimed in claim 13, wherein the outlet (510) opens out transversely,preferably perpendicularly, to the axis (A) into the reaction volume(502).
 15. A Taylor reactor as claimed in claim 13 or 14, wherein theregion (B) of the rotor (504) that is adjacent to the outlet (510)comprises means for generating a circulation flow around the axis (A).16. A Taylor reactor as claimed in claim 15, wherein the region (B) ofthe rotor (504) that is adjacent to the outlet (510) is designed in themanner of a centrifugal pump rotor.
 17. A process for convertingsubstances, where the kinematic viscosity ν of the reaction mediumincreases in the flow direction of the reactor, which comprises usingtherefor a Taylor reactor as claimed in claim
 1. 18. A process asclaimed in claim 17 for preparing sustances selected from the groupconsisting of polymers, copolymers, block polymers, graft copolymers,polycondensates, polyadducts, core/shell lattices, polymer dispersions,products of polymer-analogous reaction, including esterification,amidation and urethanization of polymers containing side groups suitablefor such reactions, olefinically unsaturated materials curable withelectron beams or ultraviolet light, or mesophases.
 19. Substancesprepared by the process of claim 17 comprising components of at leastone of moldings, films, coating materials, paints, adhesives, orsealants.